WO2010143629A1 - Concrete composition using blast furnace slag composition - Google Patents

Abstract

Disclosed is a concrete composition which is capable of securing good construction workability by suppressing decrease in fluidity of the concrete composition or decrease of air in the concrete composition over time, while suppressing the discharge amount of carbon dioxide. The concrete composition is also capable of suppressing drying shrinkage of a hardened product thereof and providing the hardened product with a necessary strength. Specifically disclosed is a concrete composition containing at least a cementitious material, water, a fine aggregate, a coarse aggregate and an admixture, wherein the blast furnace slag composition described below is used as the cementitious material at a mass ratio of water/blast furnace slag composition of 30-60%. Blast furnace slag composition: a blast furnace slag composition which is obtained by adding 0.5-1.5 parts by mass or 5-45 parts by mass of an alkali activator per 100 parts by mass of a mixture that contains 80-95% by mass of a ground granulated blast furnace slag powder having a fineness of 3,000-13,000 cm²/g and 5-20% by mass of gypsum (with the total of the blast furnace slag powder and the gypsum being 100% by mass).

Description

Concrete composition using blast furnace slag composition

The present invention relates to a concrete composition using a blast furnace slag composition. In recent years, demands for reducing carbon dioxide emissions and improving energy consumption efficiency have been increasing. In view of such circumstances, blast furnace granulated slag produced as a by-product from an ironworks is also effectively used as a raw material for blast furnace cement in the form of blast furnace slag fine powder. Generally, blast furnace cement used in concrete compositions is made by mixing ordinary Portland cement with blast furnace slag fine powder. According to JIS-R5211, depending on the amount of fine blast furnace slag powder, type A (over 5% to 30%), B type (over 30% to 60%) and C type (over 60% to 70%). Such blast furnace cement has advantages such as low heat of hydration, large long-term strength elongation, high water tightness, high resistance to chemical erosion to sulfate, and suppression effect of alkali aggregate reaction. However, the drying shrinkage is larger than that of Portland cement, and the hardened body obtained from the concrete composition using blast furnace cement is susceptible to shrinkage cracking, and it is neutralized compared to Portland cement. There is also a disadvantage that deterioration due to is fast. For this reason, as the blast furnace cement, is a situation that is used is limited to a good blast furnace cement B species of performance balance, blast furnace cement B species in a ratio of 250 ~ 450 kg in the concrete 1 m ³ In order to prepare 1 m ³ of concrete composition using Blast Furnace Cement B, about 400 kg of carbon dioxide is emitted to produce 1 ton of Blast Furnace Cement B at the factory. In this case, 100 to 180 kg of carbon dioxide is exhausted except for carbon dioxide generated by the operation of construction machines and transport of materials. Therefore, in concrete construction, technology that suppresses the generation of carbon dioxide by using finer blast furnace slag powder at a higher rate, assuming that the obtained hardened body has the required strength while ensuring workability. The appearance of is required. The present invention relates to a concrete composition using a blast furnace slag composition that meets such requirements.

Conventionally, the influence of the fineness and substitution rate of the blast furnace slag fine powder used on the concrete composition has been reported (for example, see Non-Patent Document 1). Here, when the amount of blast furnace slag fine powder used for ordinary Portland cement increases, the initial strength decreases, neutralization becomes faster, and drying shrinkage increases, compared to using ordinary Portland cement alone. It has been reported that the negative trend becomes prominent. Separately, some proposals using various admixtures in addition to such blast furnace slag fine powder have been reported (see, for example, Patent Documents 1 to 9). However, these conventional proposals, in fact, increase the amount of blast furnace slag fine powder used, 1) cannot ensure good workability, 2) it is difficult to suppress the drying shrinkage of the cured product, and 3) curing. There is a problem that it causes serious problems in some respects such as a large decrease in the compressive strength of the body.

JP-A-62-158146 Japanese Unexamined Patent Publication No. 63-2842 JP-A-1-167267 Japanese Patent Laid-Open No. 10-114555 JP 2000-143326 A JP 2003-306359 A JP 2005-281123 A JP 2007-217197 A JP 2007-297226 A

“Current Status of Concrete Technology Using Blast Furnace Slag Fine Powder,” Architectural Institute of Japan, 1992, p. 3

The problem to be solved by the present invention is to suppress the discharge amount of carbon dioxide by increasing the use ratio of blast furnace slag fine powder, while 1) lowering the fluidity of the prepared concrete composition over time and the amount of air 2) Ensure that good workability is ensured by suppressing the decrease in 2) The drying shrinkage rate of the resulting cured body is not increased compared to the case of using blast furnace cement type B, 3) The resulting cured body is The present invention is to provide a concrete composition capable of expressing necessary strength and simultaneously exhibiting the basic performances 1) to 3) above.

As a result, the present inventors have studied to solve the above-mentioned problems. As a result, as a binder, a specific blast furnace slag composition containing a high proportion of blast furnace slag fine powder and further containing gypsum and an alkali stimulant is used. We have found that the concrete composition used with the admixture is correct and suitable.

That is, the present invention is a concrete composition comprising at least a binder, water, fine aggregate, coarse aggregate and admixture, wherein the following blast furnace slag composition is used as the binder, and water / The present invention relates to a concrete composition using a blast furnace slag composition, wherein the mass ratio of the blast furnace slag composition is adjusted to 30 to 60%.

Blast furnace slag composition: per 100 parts by weight of a mixture containing 80 to 95% by weight of fine blast furnace slag powder having a fineness of 3000 to 13000 cm ² / g and 5 to 20% by weight (total 100% by weight) of gypsum, A blast furnace slag composition to which an alkali stimulant is added in an amount of 0.5 to 1.5 parts by mass or 5 to 45 parts by mass.

A concrete composition using the blast furnace slag composition according to the present invention (hereinafter referred to as the concrete composition of the present invention) contains at least a binder, water, fine aggregate, coarse aggregate and admixture. It is. The concrete composition of the present invention uses a specific blast furnace slag composition as a binder, and the blast furnace slag composition contains 80 to 95% by mass of fine powder of blast furnace slag having a fineness of 3000 to 13000 cm ² / g. And an alkali stimulant added in an amount of 0.5 to 1.5 parts by mass or 5 to 45 parts by mass per 100 parts by mass of the mixture containing 5 to 20% by mass (total 100% by mass) of gypsum It is.

The blast furnace slag fine powder has a fineness of 3000 to 13000 cm ² / g, preferably 3000 to 8000 cm ² / g, more preferably 3500 to 6500 cm ² / g. use. If a powder having a fineness outside the range of 3000 to 13000 cm ² / g is used, the fluidity of the prepared concrete composition is deteriorated, or the strength expression of the obtained cured product is lowered. In the present invention, the fineness is expressed by the specific surface area by the Blaine method.

Examples of the gypsum include anhydrous gypsum, dihydrate gypsum, and hemihydrate gypsum, and anhydrous gypsum is preferable. Any anhydrous gypsum can be used as long as it contains 90% by mass or more, and natural anhydrous gypsum, by-product anhydrous gypsum, and the like can be used. The fineness is preferably 3000 to 8000 cm ² / g, more preferably 3500 to 6500 cm ² / g.

Furthermore, examples of the alkali stimulating material include calcium hydroxide, quicklime, light-burned magnesia, light-burned dolomite, sodium hydroxide, sodium carbonate and the like. Among them, as the alkali stimulating material used in the present invention, an alkali stimulating material having a property of gradually generating calcium hydroxide when contacted with water is preferable, and as an alkali stimulating material having such properties, Portland cement is used. Most preferred. Examples of Portland cement include various Portland cements such as ordinary Portland cement, early-strength Portland cement, and moderately hot Portland cement, and general-purpose ordinary Portland cement is preferable.

In the concrete composition of the present invention, known river sand, crushed sand, mountain sand, etc. can be used as the fine aggregate, and known river gravel, crushed stone, lightweight aggregate, etc. can be used as the coarse aggregate.

In the concrete composition of the present invention, the mass ratio of the water / blast furnace slag composition is adjusted to 30 to 60%, preferably 35 to 55%. When this mass ratio is larger than 60%, the resulting cured product has too much drying shrinkage, and the strength is remarkably reduced. On the other hand, when the mass ratio is less than 30%, the fluidity of the prepared concrete composition and the amount of air over time decrease greatly, and the workability deteriorates. In the present invention, the mass ratio of water / blast furnace slag composition is determined by (mass of water used / mass of blast furnace slag composition used) × 100.

In the concrete composition of the present invention, examples of the admixture include those used for conventionally known concrete. This includes, for example, cement dispersants, drying shrinkage reducing agents, expansion materials and the like. In the concrete composition of the present invention, a cement dispersant and a drying shrinkage reducing agent, a cement dispersing agent and an expanding material, and a cement dispersing agent, a drying shrinkage reducing agent, and an expanding material can be used as an admixture.

Examples of the cement dispersant include lignin sulfonate, gluconate, naphthalene sulfonate formalin high condensate salt, melamine sulfonate formalin high condensate salt, polycarboxylic acid water-soluble vinyl copolymer, and the like. Among these, as the cement dispersant, a polycarboxylic acid-based water-soluble vinyl copolymer is preferable, and an appropriate polycarboxylic acid-based water-soluble vinyl copolymer such as the type, composition ratio, and molecular weight of the structural unit is more preferable. preferable. As such polycarboxylic acid-based water-soluble vinyl copolymers, copolymers having units formed from methacrylic acid (salt) as constituent units (for example, JP-A-58-74552 and JP-A-1-226757). And copolymers having units formed from maleic acid (salts) as constituent units (for example, JP-A-57-118058 and JP-A-63-285140). Among them, as a cement dispersant, a water-soluble vinyl copolymer having a unit formed from methacrylic acid (salt) as a structural unit is exemplified. More preferably, 45 to 85 mol% of the following structural unit A, 15 to 55 mol% of the following structural unit B, and 0 to 10 mol% of the following structural unit C in the molecule (total of 100 mol) Weight average molecular weight 2000 ~ 80000 (GPC method with a rate of), in terms of pullulan, water-soluble vinyl copolymer of the same below) is particularly preferred.

Structural unit A: One or more selected from a structural unit formed from methacrylic acid and a structural unit formed from methacrylate salt. Structural unit B: composed of 5 to 150 oxyethylene units in the molecule. Structural unit formed from methoxypolyethylene glycol methacrylate having a polyoxyethylene group Structural unit C: one or two selected from a structural unit formed from (meth) allyl sulfonate and a structural unit formed from methyl acrylate more than

The cement dispersant made of the polycarboxylic acid-based water-soluble vinyl copolymer described above can be synthesized by a known method. In the case of a copolymer having a unit formed from methacrylic acid (salt) as a constituent unit, it is synthesized by a method described in, for example, JP-A Nos. 58-74552 and 1-2226757. In the case of a copolymer having a unit formed from maleic acid (salt) as a structural unit, for example, JP-A-57-118058, JP-A-2005-132957, JP-A-2008-273766. It can be synthesized by the method described in the above. The amount of the cement dispersant composed of these polycarboxylic acid-based water-soluble vinyl copolymers is preferably 0.1 to 1.5 parts by mass per 100 parts by mass of the blast furnace slag composition.

As the drying shrinkage reducing agent, known ones can be used, and are not particularly limited, but a drying shrinkage reducing agent comprising polyalkylene glycol monoalkyl ether is preferable, and among them, one selected from diethylene glycol monobutyl ether and dipropylene glycol diethylene glycol monobutyl ether Is preferred. The amount of the drying shrinkage reducing agent used is preferably 0.2 to 4.0 parts by mass per 100 parts by mass of the blast furnace slag composition.

A well-known thing can be used as an expanding material, and it divides roughly and two types, a calcium sulfo aluminate type thing and a lime type thing, are mentioned. Any of these is an inorganic admixture that expands by producing ettringite and calcium hydroxide by a hydration reaction, and a concrete expansion material that satisfies the standard of JIS-A6202 is preferred. The amount of the expander used is preferably 10 to 25 kg per 1 m ^{3 of} the concrete composition.

When the concrete composition of the present invention is usually AE concrete entrained with 3 to 6% by volume of air, an air entrainment (AE) agent can be used as an auxiliary agent. As such AE agents, known ones can be used and are not particularly limited, but polyoxyalkylene alkyl ether sulfates, alkylbenzene sulfonates, polyoxyethylene alkylbenzene sulfonates, rosin soaps, higher fatty acid soaps, alkyl phosphate esters. Known AE agents such as salts and polyoxyalkylene alkyl ether phosphates can be used. On the contrary, when the amount of air is excessive when preparing the concrete composition of the present invention, the antifoaming agent can be used alone or in combination with the air entraining agent. As such an antifoaming agent, a known one can be used, and is not particularly limited, but an antifoaming agent such as a polyoxyalkylene glycol ether derivative, a modified polydimethylsiloxane, or a trialkyl phosphate can be used. The amount of air regulator used is preferably 0.001 to 0.01 parts by mass per 100 parts by mass of the blast furnace slag composition.

The concrete composition of the present invention can be prepared by a known method. The blast furnace slag composition, water, fine aggregate and coarse aggregate are kneaded with a mixer, while the above cement dispersant, drying shrinkage reducing agent, expansion It is preferable to mix a material, an air amount adjusting agent and the like appropriately and dilute with water, and then knead both. In preparing the concrete composition of the present invention, additives such as a curing accelerator, a setting retarder, a rust preventive, a waterproofing agent, and a preservative are used in combination, as long as the effects of the present invention are not impaired. You can also

According to the concrete composition of the present invention described above, the obtained cured product is drying shrinkage is that of 800 × 10 ^-6 or less. The concrete composition of the present invention can be applied not only as a concrete composition placed at a construction site, but also as a concrete composition for a secondary product processed in a concrete product factory.

According to the present invention, while suppressing the amount of carbon dioxide emission in preparing a concrete composition, the deterioration of fluidity and the amount of air over time of the prepared concrete composition is suppressed to ensure good workability. Further, there is an effect that drying shrinkage of the obtained cured product can be suppressed, and further, the strength necessary for the obtained cured product can be expressed.

Hereinafter, in order to make the configuration and effects of the present invention more specific, examples and the like will be described. However, the present invention is not limited to the examples. In the following examples and the like, unless otherwise indicated,% means mass%, and part means mass part.

Test Category 1 (Synthesis of water-soluble vinyl copolymer)
Synthesis of water-soluble vinyl copolymer (p-1) 60 g of methacrylic acid, methoxypoly (23 oxyethylene units, hereinafter n = 23) ethylene glycol methacrylate 300 g, sodium methallylsulfonate 5 g, 3-mercapto After charging 4 g of propionic acid and 490 g of water into the reaction vessel, 58 g of a 48% aqueous sodium hydroxide solution was added, and the mixture was partially neutralized with stirring and dissolved uniformly. After the atmosphere in the reaction vessel was replaced with nitrogen, the temperature of the reaction system was maintained at 60 ° C. in a warm water bath, 25 g of a 20% aqueous solution of sodium persulfate was added to start radical polymerization reaction, and the reaction was continued for 5 hours. The reaction was terminated. Thereafter, 23 g of a 48% sodium hydroxide aqueous solution was added to completely neutralize the reaction product, and a polycarboxylic acid-based water-soluble vinyl copolymer (p-1) having units formed from methacrylate as structural units. A 40% aqueous solution was obtained. Analysis of the water-soluble vinyl copolymer (p-1) revealed that it was formed from a structural unit formed from sodium methacrylate / a structural unit formed from methoxypoly (n = 23) ethylene glycol methacrylate / sodium methallylsulfonate. It was a water-soluble vinyl copolymer having a mass average molecular weight of 33,800 in the proportion of structural unit = 70/27/3 (mol%).

Synthesis of water-soluble vinyl copolymers (p-2) to (p-4) and (pr-1) to (pr-4) In the same manner as the synthesis of water-soluble vinyl copolymer (p-1), Water-soluble vinyl copolymers (p-2) to (p-4) and (pr-1) to (pr-4) were synthesized. The contents of each water-soluble vinyl copolymer synthesized above are summarized in Table 1.

In Table 1,
Structural units A to C: indicated by monomers that form each structural unit.
A-1: Sodium methacrylate A-2: Methacrylic acid B-1: Methoxypoly (n = 23) ethylene glycol methacrylate B-2: Methoxypoly (n = 68) ethylene glycol methacrylate B-3: Methoxypoly (n = 9) ethylene Glycol methacrylate C-1: Sodium methallyl sulfonate C-2: Sodium allyl sulfonate C-3: Methyl acrylate

Test Category 2 (Preparation of blast furnace slag composition)
A blast furnace slag composition (S-1) to (S-10) and (R) was prepared by mixing blast furnace slag fine powder, anhydrous gypsum and an alkali stimulant under the blending conditions shown in Table 2. -1) to (R-10) were obtained.

In Table 2,
sg-1: Blast furnace slag fine powder with a fineness of 4100 cm ² / g sg-2: Blast furnace slag fine powder with a fineness of 5900 cm ² / g sg-3: Blast furnace slag fine powder with a fineness of 1020 cm ² / g gp- 1: Anhydrous gypsum with a fineness of 4150 cm ² / g gp-2: Anhydrous gypsum with a fineness of 5800 cm ² / g rc-1: Normal Portland cement rc-2: Early strength Portland cement

Test category 3 (Preparation of concrete composition)
Examples 1-36
Under the mixing conditions shown in Table 3, in a 50-liter pan-type forced kneading mixer, kneaded water (tap water), blast furnace slag composition, fine aggregate (Oikawa water system river sand, density = 2.58 g / cm ³ ) In addition, each predetermined amount of admixture such as cement dispersant, drying shrinkage reducing agent, expansion material, etc. is added, and an air amount adjusting agent (AE agent manufactured by Takemoto Yushi Co., Ltd., trade name AE-300). ) And kneaded for 45 seconds. Finally, a predetermined amount of coarse aggregate (Okazaki crushed stone, density = 2.68 g / cm ³ ) is added and kneaded for 60 seconds. The target slump is 18 ± 1 cm and the target air amount is 4.5 ± 1%. A concrete composition having a water / blast furnace slag composition mass ratio of 45% or 40% was prepared.

Comparative Examples 1-27
A concrete composition having a water / blast furnace slag composition mass ratio of 45% was prepared by the same mixing method as in the example under the blending conditions shown in Table 4.

Comparative Examples 28 and 29
A concrete composition having a water / blast furnace cement mass ratio of 45% or 50% using blast furnace cement type B was prepared by the same mixing method as in the examples under the blending conditions shown in Table 4.

In Table 3 and Table 4,
Carbon dioxide emissions: Carbon dioxide emissions (kg) when producing 1 m ³ of concrete composition. However, the value calculated from the amount of Portland cement used excluding the amount of carbon dioxide emissions derived from the energy required for the production of gypsum Type of cement dispersant: water-soluble vinyl copolymer listed in Table 1 or the following P -5
P-5: As a cement dispersant made of a polycarboxylic acid-based water-soluble vinyl copolymer, trade name Tupol HP-11W (maleic acid and α-allyl-ω-methyl-polyoxyethylene Copolymer salt)
Amount used: part by mass as solid content of cement dispersant, drying shrinkage reducing agent or expansion material per 100 parts by mass of blast furnace slag composition (Comparative Examples 28 and 29 are blast furnace cement type B) Type of blast furnace slag composition: Items listed in Table 2 * 1: Diethylene glycol monobutyl ether * 2: Dipropylene glycol diethylene glycol monobutyl ether * 3: Trade name made by Taiheiyo Materials Co., Ltd. is Taiheiyo Hyperexpan (lime-based expansion material)
* 4: Blast furnace cement type B (density = 3.04 g / cm ³ , brain value 3850 cm ² / g)

Test category 4 (Evaluation of prepared concrete composition)
About the prepared concrete composition of each example, the air content, slump, and slump residual rate were calculated | required as follows. Moreover, about the hardening body obtained from each concrete composition, the drying shrinkage rate and the compressive strength were calculated | required as follows.

Air content (volume%): The concrete composition immediately after kneading and the concrete composition after standing for 60 minutes were measured according to JIS-A1128.
Slump (cm): Measured according to JIS-A1101 simultaneously with the measurement of the air amount.
-Slump residual rate (%): (slump after standing for 60 minutes / slump immediately after kneading) x 100.
Drying shrinkage rate: In accordance with JIS-A1129, dry shrinkage strain was measured by a comparator method on a 26-week-old specimen in which the concrete composition of each example was stored at 20 ° C. × 60% RH and dried. Shrinkage was determined. The smaller this value, the smaller the drying shrinkage.
Compressive strength (N / mm ² ): The concrete composition of each example was measured at a material age of 7 days and a material age of 28 days in accordance with JIS-A1108.

The results are summarized in Tables 5 and 6. The concrete composition of the present invention prepared in each example has less carbon dioxide emission for producing 1 m ³ of the concrete composition than the case where the blast furnace cement type B is used, and the concrete composition is deteriorated over time. The resulting cured product has a drying shrinkage ratio of less than 800 × 10 ⁻⁶ and a sufficient compressive strength required.

In Table 6,
Comparative Examples 1, 2, 6, 7, 21 to 23 and 25 to 27: Measurement was not performed because the target fluidity (slump value) was not obtained.

Claims (11)

A concrete composition comprising at least a binder, water, fine aggregate, coarse aggregate and admixture, wherein the following blast furnace slag composition is used as the binder, and water / the blast furnace slag composition: A concrete composition using a blast furnace slag composition, wherein the mass ratio is adjusted to 30 to 60%.
Blast furnace slag composition: per 100 parts by weight of a mixture containing 80 to 95% by weight of fine blast furnace slag powder having a fineness of 3000 to 13000 cm ² / g and 5 to 20% by weight (total 100% by weight) of gypsum, A blast furnace slag composition to which an alkali stimulant is added in an amount of 0.5 to 1.5 parts by mass or 5 to 45 parts by mass. The concrete composition using the blast furnace slag composition according to claim 1, wherein the alkali stimulating material is Portland cement. The concrete composition using the blast furnace slag composition according to claim 1 or 2, wherein the gypsum is anhydrous gypsum. The concrete composition using the blast furnace slag composition according to any one of claims 1 to 3, wherein the fine powder of the blast furnace slag has a fineness of 3500 to 6500 cm ² / g. The cement dispersant comprising a polycarboxylic acid-based water-soluble vinyl copolymer is contained as at least a part of the admixture at a ratio of 0.1 to 1.5 parts by mass per 100 parts by mass of the blast furnace slag composition. A concrete composition using the blast furnace slag composition according to any one of items 1 to 4. The polycarboxylic acid-based water-soluble vinyl copolymer contains 45 to 80 mol% of the following structural unit A, 15 to 55 mol% of the following structural unit B, and 0 to 10 mol of the following structural unit C in the molecule. The concrete composition using the blast furnace slag composition according to any one of claims 1 to 5, having a weight average molecular weight of 2000 to 80000 in a ratio of% (total 100 mol%).
Structural unit A: one or more selected from structural units formed from methacrylic acid and structural units formed from methacrylates Structural unit B: polyoxyethylene composed of 5 to 150 oxyethylene units Structural unit formed from methoxypolyethylene glycol methacrylate having a group Structural unit C: One or two or more selected from a structural unit formed from (meth) allyl sulfonate and a structural unit formed from methyl acrylate The dry shrinkage reducing agent comprising a polyalkylene glycol monoalkyl ether as at least a part of the admixture is contained in a proportion of 0.2 to 4.0 parts by mass per 100 parts by mass of the blast furnace slag composition. A concrete composition using the blast furnace slag composition according to any one of the items. The concrete composition using a blast furnace slag composition according to claim 7, wherein the drying shrinkage reducing agent is one or more selected from diethylene glycol monobutyl ether and dipropylene glycol diethylene glycol monobutyl ether. The concrete composition using the blast furnace slag composition according to any one of claims 1 to 8, which contains, as at least a part of the admixture, an expansion material at a rate of 10 to 25 kg per 1 m ^{3 of} the concrete composition. The concrete composition using the blast furnace slag composition according to any one of claims 1 to 9, wherein the mass ratio of the water / blast furnace slag composition is adjusted to 35 to 55%. The concrete composition using the blast furnace slag composition according to any one of claims 1 to 10, wherein the obtained cured product has a drying shrinkage of 800 × 10 ^-6 or less.